Microbiology Flashcards
(34 cards)
Outer surface (cell wall/ membrane) of viruses, bacteria, fungi and protozoa/ helminths
Viruses: Protein capsid made up of capsomeres
Bacteria: Cell wall made up of peptidoglycan
Fungi: Cell wall made up of chitin
Protozoa and helminths: flexible membrane
Helminths
Multicellular worms that infest body, mainly GI tract.
Transmission can be direct or indirect via an intermediate non-human host.
Protozoa
Single cell organisms. Have a dormant and active stage. Acquired by contaminated water.
Fungi
Single cell or brainched or both organisms. Have a cell wall made up of chitin. Disease caused by environment or part of the normal flora.
Bacterial cell wall structure
Multilayered structure mainly composed of peptidoglycans, which is glycan chain and tetrapeptide chain.
Difference between Gram + and Gram - cell wall
Gram +: thick cell wall, no outer membrane or lipopolysaccharides, no porins. Gram -: Thin cell wall, outer membrane containing lipopolysaccharides, as well as porins.
Structure of capsule in Bacteria
gelatinous layer outside cell wall made up of polysaccharides.
Determinant of virulence. Helps with adherence. Helps with identification of a bacteria in lab.
2 Roles of pilli
- Attachement
- Conjugation (sexual reproduction)
Spores in Bacteria
produced by some gram positive bacteria, highly resistant structures resistant to harsh conditions.
Components of viruses
DNA or RNA genome, capsid core, polymerase protein. Sometimes envelope.
name of the viral genome enclosed by capsid protein coat
and
Subunits of capsid
nucleocapsid
capsomeres
Icosahedral capsid
made up of 20 equilateral triangular faces arranged around the surface of a sphere. Each triangle is made of min 3 proteins.
Helical capsid
Proteins are arranged in a helix around the DNA.
Viral Envelope
Lipid bilayer from host cell membrane surrounding certain viruses.
Has glycoproteins attached to its surface (spikes). It determines the stability of virus: enveloped ones cannot live outside host.
Importance of viral surface protein
Attach to membrane proteins and binding sites for antibodies.
Describe the three types of symbiotic associations : Commensalism, mutualism and parsitism
Commensalism: one benefits other whatevs Mutualism: both benefit Parasitism: one benefits at expense of other
Opportunistic infections
Causes by non pathogenic microorganisms that act as pathogen in certain circumstances.
E.g. normal flora in other part of body, immunicompromisation, lack of normal flora.
Microbial pathogenesis
The process by which infection leads to disease
Immunopathogenesis
When pathology is caused by overwhelming immune response.
E.g. cytotoxic T Cell mediated attack, antibody-mediated damage to the host, antibody mediated complement fixation
Stages of infectious disease (4)
Incubation Prodrome Illness Recovery
Communicable vs non communicable disease.
Communicable: Transmissible (directly or indirectly)
Non communicable: non transmissible to humans.
Nosocomial infections
Infections acquired in a hospital or medical facility.
Iatrogenic infections
Infection caused by distruption to the body’s normal mechanical barriers
e.g. injury associated with therapy, metal/ plastic implants
Molecules on bacteria that attach to the host cells and how Viruses attach to host cells
bacteria: Adhesins
Viruses have proteins that bind to receptros on the host cell membrane. This induces a conformational change that leads to membrane penetration. They also have attachement factors which help viruses concentrate at the cell surface.
